WO2004103921A1 - Articles en verre et en vitroceramique et procede de fabrication - Google Patents

Articles en verre et en vitroceramique et procede de fabrication Download PDF

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Publication number
WO2004103921A1
WO2004103921A1 PCT/BR2004/000079 BR2004000079W WO2004103921A1 WO 2004103921 A1 WO2004103921 A1 WO 2004103921A1 BR 2004000079 W BR2004000079 W BR 2004000079W WO 2004103921 A1 WO2004103921 A1 WO 2004103921A1
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Prior art keywords
glass
fact
process according
sintering
frits
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PCT/BR2004/000079
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English (en)
Inventor
Dutra Zanotto Edgar
Eduardo Bellini Ferreira
Cátia FREDERICCI
Miguel Oscar Prado
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Universidade Federal De São Carlos-Ufscar
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Publication of WO2004103921A1 publication Critical patent/WO2004103921A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
    • C03C1/002—Use of waste materials, e.g. slags
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/06—Other methods of shaping glass by sintering, e.g. by cold isostatic pressing of powders and subsequent sintering, by hot pressing of powders, by sintering slurries or dispersions not undergoing a liquid phase reaction
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B32/00—Thermal after-treatment of glass products not provided for in groups C03B19/00, C03B25/00 - C03B31/00 or C03B37/00, e.g. crystallisation, eliminating gas inclusions or other impurities; Hot-pressing vitrified, non-porous, shaped glass products
    • C03B32/02—Thermal crystallisation, e.g. for crystallising glass bodies into glass-ceramic articles
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
    • C03C10/0036—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition containing SiO2, Al2O3 and a divalent metal oxide as main constituents
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
    • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
    • C03C3/087—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal containing calcium oxide, e.g. common sheet or container glass

Definitions

  • the present invention refers to glass and glass- ceramic articles and to a process for obtaining same through melting, fritting, milling and particle size distribution adjustment of colorless and colored glasses of the soda-lime- silica Na 2 0-CaO-S ⁇ 0 2 (NCS) system, and further mixture of the frits according to color or particle size distribution criteria, compaction in refractory molds, viscous flow sintering thermal treatment and, for glass-ceramics, simultaneous or subsequent crystallization.
  • NCS soda-lime- silica Na 2 0-CaO-S ⁇ 0 2
  • Sintering treatments with or without concurrent crystallization can be designed and optimized using mathematical models and algorithms via computer simulations developed specifically for this purpose.
  • properties of the so- obtained products are similar to those of present glass-ceramics, the fact of being based on a different chemical system - soda- lime-silica having compositions very close to those of window or container glasses, renders the present product as good as, but cheaper than other glass-ceramics.
  • the proposed process makes possible to obtain monolithic, sintered pieces of variable porosity, from very low (close to zero) up to the order of 40% by volume.
  • the invention is therefore also directed to glass or glass-ceramic articles resulting from the inventive process.
  • Such materials can be obtained through a conventional, three-step method: melting, shaping and thermal treatments for crystal nucleation and growth in the volume of material. In this case the introduction of nucleating agents in the glass composition is generally required.
  • another well-known method comprises the sintering of powdered glasses, with simultaneous or 5 subsequent superficial crystallization of the glassy particles.
  • This second method is that it does not require nucleating agents in the glass composition, since the vitreous particle surfaces themselves work favorably towards this end.
  • Sintering allows obtaining glass-ceramic pieces y ⁇ 5 of complex shapes such as design articles, kitchen appliances, basin cubs, sanitary articles, among others, of wide size scale, besides products of simpler geometry, such as flat or curved plates (floor and wall tiles) .
  • the resulting products can be white or colored, 25 polished or rugged, are attractive - due to their similarity to natural stones - and are fairly resistant to chemicals as well as to failure and scratching. Such products can be used instead of the conventional ceramic wall and floor tiles or translucent natural stones such as marble and granite. 30
  • the patent literature is abundant in publications on glass and glass-ceramics for tiles.
  • the composition of the employed frit was (wt. %) 19.1 CaO, 6.8 Al 2 0 3 , 59.1 Si0 2 , 1.7 Na 2 0, 0.6 B 2 0 3 , 6.8 ZnO and 4.3 BaO.
  • • 15 such frit is admixed to a black frit containing 5 wt . % Fe 2 0 3 , so as to obtain a black spot glass-ceramic after sintering.
  • US patent 3,964,917 broadens the formulation of US 3,955,989 into (wt.) 15-25% CaO, 3-13% A1 2 0 3 , 50-60% Si0 2 , 2-10% ZnO, including further variable amounts of minor elements.
  • transition element oxides 35 small amount ( ⁇ 0.1%) of transition element oxides.
  • these colored frits are cited the formulations (wt. %) 15-25 CaO, 15-25 A1 2 0 3 , 40-59 Si0 2 , 0-12 MgO, 0-12 ZnO, 2-10 B 2 0 3 , 4-13 Na 2 0, 0-5 K 2 0, 0-5 BaO, 0-1 As 2 0 3 , 0-1 Sb 2 0 3 + transition oxides.
  • Additional glass-ceramics can be obtained from diopside (CaO. gO.2Si0 2 ) , with potential resistance to chemical attack and mechanical strength higher than those of wollastonite, hence the interest in these materials.
  • Bulgarian patent BG50879 relates to a process
  • JP 9086942 teaches a process similar to those
  • milled glasses that may originate from recycled television tubes, flat or container glasses, having compositions in the range (wt. %) 55-82 Si0 2 , 1-4 A1 2 0 3 , 2-16 Na 2 0, 0-10 K 2 0, 0-5 MgO, 0-12 CaO, 0-3 PbO, 0-15 BaO, 0-15 B 2 0 3 , 0-11 SrO, 0-1 ZnO, 0-3 Zr0 2 , 0-1 Ti0 2 , 0-1 Ce0 2 , 0-1 Sb 2 0 3 , 0-1 As 2 0 3 and 0-1 F, of particle size
  • a mineral component or a mixture of same is added, selected among of limestone, sand, recycled ceramic materials or slag, at particle sizes distributed under 0.4 mm, and of from 0 to 5% of fine additives ( ⁇ 60 ⁇ m) , that can be Zr0 2 , MgO, SnO, CaO, Ti0 2 , kaolin and ZrSi0 4 , or still, inorganic pigments, metal 5 oxides, colorless or colored glasses or powdered metals.
  • ⁇ 60 ⁇ m fine additives
  • Also added is from 1 to 3% water to implement the mixture and avoid segregation, such water being later on eliminated by drying the material in the molds at temperatures between 60 and 110°C before sintering.
  • US patent 5,536,345 teaches a process similar to those previously described but using complex thermal treatments and three layers: a sand layer at the bottom of the refractory mold, another one of crushed glass of several origins such as
  • the present application presents the manufacture of frits (that is, a glass of controlled composition, that melts at pre-determined temperatures and times, sufficient for the complete reaction between the raw materials and homogenization, and is quickly cooled and milled at previously designed particle size distributions) especially for sintering and simultaneous or subsequent crystallization, in this way avoiding problems with dirt and heterogeneity.
  • frits that is, a glass of controlled composition, that melts at pre-determined temperatures and times, sufficient for the complete reaction between the raw materials and homogenization, and is quickly cooled and milled at previously designed particle size distributions
  • the process for obtaining glasses or glass-ceramics from colorless and colored glasses of the soda-lime-silica Na 2 0-Ca0-Si0 2 (NCS) system is rigorously designed, with strict control of the sintering and crystallization degrees, by obtaining thermal treatment parameters through computer simulations, using an algorithm specially developed by the Applicant for this purpose.
  • Detailed descriptions of such algorithm can be found in several publications by the same authors of the present application.
  • One of these publications is the article by E.D. Zanotto and M.O Prado, "Isothermal sintering with concurrent crystallization of monodisperse and polydispersed glass particles".
  • the present invention relates to a process for obtaining glass and glass-ceramic articles by the mixture of the raw materials, melting, fritting, milling and particle size distribution adjustment of colorless and colored glasses of the soda-lime-silica (NCS) - Na 2 0-Ca0-Si0 2 - system and then, mixture of the frits according to coloring or particle size distribution criteria, compaction in refractory molds, sintering treatment between 720°C and 1100°C, so as to favor viscous flow before the limiting occurrence of the superficial crystallization, for obtaining maximum densification or alternatively interrupting sintering by temperature reduction to obtain highly porous materials and, in case of the glass-ceramics, simultaneous or subsequent crystallization, with the aid of a mathematical model and algorithm for computer simulation in order to obtain the desired porosity and crystallinity .
  • NCS soda-lime-silica
  • the present invention provides a process for obtaining glass or glass-ceramic articles based on the soda- lime-silica system by mixing the raw materials, melting, fritting, milling and particle size distribution adjustment of colorless and colored glasses and further mixture of the frits, compaction and sintering thermal treatment with the aid of a mathematical model and computer simulation algorithm, the sintering occurring with or without crystallization.
  • the invention provides still a process for obtaining glass or glass-ceramic articles based on the NCS system where the thermal treatment process is rigorously designed, having a strict control of the sintering and crystallization degree, through computer simulations using an algorithm developed by the Applicant.
  • the invention provides further a process for obtaining glass or glass-ceramic articles based on the NCS system that makes possible to obtain sintered monolithic pieces of variable porosity, from very low (close to zero) and up to the order of 40% of the volume.
  • the invention provides still a process based on the above-mentioned numerical simulation for obtaining glass or glass-ceramic materials based on the NCS system that favors the viscous flow sintering before the limiting occurrence of the superficial crystallization.
  • the invention provides also glass or glass- ceramic articles based on the NCS system having typical features of 3 point bend strength of from 40 to 100 MPa, Vickers Microhardness 500 to 600 Pa, and chemical durability (% by weight loss) in the presence of 0.01 M HC1 (95°C/1 h) 0.1 to 0.3 and in the presence of 0.01 M NaOH (95°C/1 h) , 0.2 to 0.6.
  • FIGURE 1 attached is a flowsheet that illustrates the process of the invention.
  • FIGURE 2 attached is a flowsheet that illustrates the algorithm developed by the Applicant and used in the invention.
  • the glass- ceramic materials resulting from the proposed process are called NCS-based glass-ceramics, in an abbreviated form, glass- ceramics/NCS or GC/NSC
  • soda-lime-silica (NCS) system is technologically very important since conventional packaging and window glasses and others commodity glasses having diverse applications are derived from said system.
  • the wide application of this system is due to the combination of excellent properties such as chemical stability, transparency (even if the glasses can also be colored and even opaque) , abrasion resistance and thermal insulation .
  • Na 2 0, CaO and Si0 2 convey the name to this class of materials
  • other components are added to the composition in order to adjust the required properties to the manufacture and further use.
  • an example of typical average composition in this system is (wt. %) 72 Si0 2 , 14 Na 2 0, 11 CaO, 1 MgO and 2 A1 2 0 3 .
  • a small amount (0.1 wt . %) of sulfates is also added to help removing bubbles.
  • the combination of Na 2 0, CaO, A1 2 0 3 and Si0 2 is used to suppress the liquid-liquid immiscibility occurring in binary systems of alkaline and alkaline-earth silicates and thus prevent the liquid-liquid phase separation that degrades the hydrolytic resistance of these materials, besides reducing the tendency to devitrification.
  • crystallization mainly produces the crystalline phases crystoballite (Si0 2 ) and devitrite (Na 2 0.3Ca0.6Si0 2 ) , that convey to the material improved hardness and abrasion strength.
  • the satisfactory manufacture of these materials by sintering at temperatures below 1100°C has been made possible only after the progress of the knowledge and control of the viscous flow sintering and concurrent crystallization kinetics.
  • the process for producing sintered glass and glass-ceramic materials from glasses of the soda-lime-silica (NCS) comprises the following steps: i) Providing raw materials for the manufacture of controlled composition frits, mixing the raw materials, melting at controlled temperatures between 1300°C and 1600°C, for predetermined periods of time, homogenizing, refining and quickly cooling (fritting) in water or in rolls (or any other process for the manufacture of particulate glasses) so as to obtain frits, beads or pellets; colored frits can be obtained based on the composition of colorless frit, by adding small percentages of transition elements: Fe, Cr, Co, Ni, Ti, V, Mn, Cu; or rare-earths (Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) ; ii) Milling at previously designed particle sizes, smaller than 15 mm, and effect the particle size distribution adjustment of the particulate material according to the aesthetic design and porosity of the final article
  • particle size distributions with average size around ⁇ 4 mm can lead to granite-like glass-ceramics; iii) Admixing the colorless and colored glass particles according to the design of the final article; iv) Settling the particulate material using gravity or vibration in refractory molds; of from 1 to 5% by weight of conventional lubricants and water being added to the mixture in order to maximize the particle packing and avoid segregation; v) Thermally treating the so settled material to sinter by viscous flow with or without simultaneous crystallization between 720°C and 1100°C, densification and partially or completely crystallizing the materials, so as to obtain glass or glass-ceramic monoliths; vi) Optionally, effect rectification and polishing of the materials obtained after sintering,
  • the manufacturing process of glass and glass- ceramic objects through sintering starts with the preparation of particulate glasses (that can be crystallized in the process, in the case of the glass-ceramics) especially produced to this end.
  • Such glasses are manufactured based on commercial raw materials (sand, sodium, calcium and magnesium carbonates, alumina, etc) that, after melting, yield frits having components in the composition intervals listed in Table 1.
  • a specific example is the above-cited composition (weight %) 72 Si0 2 , 14 Na 2 0, 11 CaO, 1 MgO and 2 Al 2 0 3 .
  • a small amount from 0.1 to 2% by weight is also added to help removing bubbles.
  • Impurities the content of which is lower than 0.01% by weight are not listed in this Table and are a function only of the purity of the raw materials employed.
  • the cullet produced at some industry and not packed off as an end product, but often recycled into same, is also suitable for milling and preparing particles for sintering; skipping the step of frit preparation.
  • One kind of glass useful for making frits for the sintering process according to the invention is flat soda-lime- silica glass.
  • Sb 2 0 3 can aid in eliminating pore-generating dissolved gases.
  • a further possibility that results in a relevant effect is to include certain amounts of the components A1 2 0 and MgO into the frit composition, in order to minimize its tendency to crystallization during sintering - again aiming at minimizing pores. These two oxides also improve the chemical durability.
  • the compositions suggested in the present specification are based on conventional average compositions of NCS glasses, since the concept of the invention is not directed to a new composition, but instead to the application of known compositions to the described process.
  • the patentably distinguishing aspect of the invention in the frit manufacturing step is that the glass is of a controlled composition, being melted at pre-determined temperatures and periods of time, quickly cooled, milled and assembled at previously designed particle size distributions, especially for sintering with or without concurrent crystallization.
  • the glass can be partially or completely recycled, provided it obeys the composition and melting criteria of the described process.
  • Components Compos ition (wt % )
  • the raw materials are mixed and melted between 1300°C and 1600°C, with the melt being quickly cooled for the manufacture of granulated glasses (frits) .
  • Granulated glasses are generally manufactured as frits, by the forced cooling of the molten glass poured into water
  • the next step for manufacturing glasses or glass- ceramics by sintering corresponds to the particle size distribution adjustment.
  • the control of the particle size distribution of the particulate material is paramount to obtain sintered materials of minimum porosity, or having the suitable porosity for the desired use.
  • Porosity is determining of the mechanical strength, of the staining resistance and of the visual aspect of the materials used for tiles and floors.
  • the particle size distribution will be duly selected with the aid of the algorithm described in the scientific articles cited hereinbefore.
  • the porosity does not definitely intervene in the utilization of the material.
  • low porosity ⁇ 5%
  • thermal insulating materials where a high residual closed porosity is desirable.
  • specific dimension pores is of paramount importance. It is also noticed that the presence of a controlled porosity in the volume of the piece can diminish the total density, resulting in lighter materials for building.
  • the frits directed to the manufacture of glass or glass-ceramic articles resulting from the inventive process should contain particles below 15 mm, in order to obtain different textures in the end product, as well as for the porosity control of the piece.
  • the frits can be comminuted in crushers and mills, separated by sieves into different particle size ranges and again mixed according to a suitable project of particle size distribution.
  • the material can be comminuted and separated between the limits of a certain particle size distribution, or below a maximum size, using the total of the so- collected material, which will possess a nearly continuous distribution of particle sizes between the chosen limits.
  • This kind of frit processing is of an easier industrial implementation, since it simplifies the sieving and particle size distribution separation process, while eliminating the disposal of particles having not designed sizes and need of a further mixing step of the selected particle size distributions.
  • the control of the article end properties is somehow limited.
  • the separation process and particle size distribution adjustment can yield materials having particle sizes that are not within the desired particle size distribution, but that can be recycled and re-melt during the process of frit manufacture .
  • the mixture of the particulate material is a step that depends on the desired properties and aesthetic features in the obtained pieces, such as for example, the combination of colors and texture.
  • a further expected effect is to harmonize in the product an attractive visual aspect with a suitable mechanical performance, such as fracture strength.
  • the mixture of the particulate frit(s) can be effected in industrial, conventional mixers. Mixtures of different colors or particle size distributions can be placed in the molds in superimposed layers to yield certain effects in the end product. For example, the addition to the compact surface of a particle layer with sizes of the order of 5 to 10 mm, and after sintering, carrying out grinding and polishing at a depth that is half the final surface thickness can minimize the porosity of this area, as will be explained below.
  • the shaping process for sintered glasses and glass-ceramics is much simpler than the pressing in molds of the particulate material, with addition of binders and further lubricant, this being the process generally used in the manufacture of ceramic tiles.
  • the particulate glass is placed in refractory molds, previously coated with a finely particulate material, such as an alumina or kaolin aqueous suspension, which is dried before the frits placement, in order to avoid adherence of the glass to the mold.
  • Compaction of the pieces can be effected just by gravity action, aided by the forced vibration of the particles in the refractory trays.
  • up to 5 wt % water can be added to the glass mixture and, through capillarity, aid in the particle packing.
  • the material before sintering, the material should be dried between 60 and 110°C, as taught in US patent 5,649,987.
  • Refractory molds should be dimensioned so as to compensate for the piece retraction, up to 40% by volume, caused by sintering. The retraction is not isotropic, but mainly at the height of the piece, this being caused by gravity action on the fluency of the glass material.
  • the sintering thermal treatment is conveniently planned with the aid of the above-cited algorithm.
  • the sintering thermal treatment is carried out between 720°C and 1100°C, depending on the specific glass composition, on the particle size distribution and on the final desired porosity.
  • the materials manufactured according to the present process have lower sintering/crystallization temperatures
  • the temperature should be homogenous throughout the piece .
  • the treating time at some temperature also varies according to the specific chemical composition or the parent glass, the frit size distribution and the desired properties of the end product, and can vary from a few minutes to hours.
  • the heating can be isothermal by instantaneously inserting the compact in a furnace previously set to the desired sintering temperature and holding the material for half to several hours .
  • the sintering step can be non- isothermal, i.e. if the heating rate of the compact is between 1 and 20°C per minute.
  • the material is not promptly sintered at 100% of the theoretical density, or up to a minimum porosity, without a reasonable glass formulation strategy, care in the manufacture of dense frits, a suitable project of particle size distribution in the compact and planning of the thermal treatments, so as to privilege the viscous flow sintering before the limiting occurrence of the superficial crystallization. This applies if maximum densif.ication is desired, but if the desired aim is a high porosity, at a certain moment it is possible to wish to interrupt sintering or accomplish it at a suitable rate .
  • Rectifying and polishing are usual steps at the end of the manufacture of ceramic tiles of the porcelanatto kind, glass-ceramics or even in the superficial finishing of natural rocks. Polishing is a highly-sought feature by consumers, since besides the highly aesthetic gloss, cleaning is also made easier.
  • One way of minimizing the superficial porosity of the manufactured pieces is by adding, at the compact surface, a layer of particles having sizes of the order of 5 to 10 mm and, after sintering, further grinding and polishing at a depth of the order of half the thickness of the resulting layer, formed by the outer particles. This therefore occurs at the layer that contacts the surface and nearly all the porosity is eliminated by the path opened to the atmosphere. Pores entrapped due to the fast viscous flow (if the effect of surface crystallization is delayed in this step) are located only below this layer, in the final densification steps.
  • the outer layer has a sufficient thickness, allowing grinding and polishing at a depth approximately half this thickness (that is why particles of the order of 5 to 10 mm are used) , it is possible to obtain a smooth surface, free from porosity, this being highly desirable in the case of wall and floor tiles, chiefly of lighter colors.
  • Polishing can be accompanied by rectification for dimensional adjustment.
  • Glass-ceramics are manufactured by the superficial crystallization of the glass particles, obtained by keeping the piece in the furnace, after sintering and initial densification, at a sufficiently high temperature so as to allow crystal growing at the desired rate and during a sufficient period of time to attain the crystallized fraction designed for the specific material.
  • the flowsheet of Figure 1 illustrates the several process steps of the invention, that is, at 1, the mixture of raw materials, 2, melting, homogenization and refining, 3, fritting or granulation, 4, comminuting, 5, separation and particle size distribution adjustment, 6, mixture, 7, shaping in refractory molds, 8, sintering/crystallization, that leads to the natural end product 9 or to a polishing/rectification step 10 and to the polished end product 11.
  • One important aspect of the invention is the use of a mathematical model or algorithm that eliminates for the most part the empirical approach used in state-of-the-art processes for obtaining sintered glass and glass-ceramics articles.
  • the mathematical model by considering the concurrent crystallization of the surface (and volume, if it is the case) during sintering allows to calculate the suitable thermal treatment in terms of time and temperature in order to obtain the desired porosity and crystallinity for the compact body, as detailed in the above-cited articles .
  • densification curves can be calculated as a function of time for different temperatures with the aid of known equations. Such curves take into consideration the effect of the superficial crystallization on sintering. Further, the model allows one to draw time versus temperature curves that lead to working windows (time, temperature or heating rates), which allow the establishment of desired conditions of density and crystallinity .
  • viscosity, surface tension, number of nucleation sites per unit area, crystal growth rate, particle size distribution, green density, time, temperature and heating rate are entry parameters for the algorithm response, which are density or porosity, and crystallinity.
  • the algorithm can indicate the best or the most promising conditions for sintering, such as dwell time, temperature and particle size distribution, for obtaining articles having the desired properties.
  • sintering such as dwell time, temperature and particle size distribution
  • the algorithm used in the invention and described in detail in the above-cited articles comprises the following steps: i) entry of the physical chemical parameters referring to the frit composition, that is, viscosity as a function of temperature ( ⁇ (T) ) and glass surface tension ( ⁇ ) that can be measured or calculated, besides the crystal growing rate of each of the crystalline phases found in the material (u x (T)), that shall be measured; ii) entry of the parameters referring to the manufacture process steps, that is, the particle size distribution v(r), the number of superficial nuclei for crystallization of each different crystalline phase found in the material (Ns and the green density of the compact (p v ) , that should be measured, besides the thermal treatment parameters time (t) , temperature (T) and heating/cooling rate (q) ; iii) processing of the algorithm with the entry data, yielding as response the density or porosity, as well as the compact crystallized superficial fraction after thermally treating under the specified conditions; iv) alternatively,
  • Table 2 shows an example of a glass composition leading to a glass-ceramics of good mechanical and physical chemical performance.
  • particulate glass - having the particle size distribution listed in Table 3 below - is sintered at 720°C for 2 hours without controlled cooling as refers to densification and crystallization, but sufficiently slow (l-5°C/min) to avoid cracking of the piece by thermal shock and to release tensions in the residual glass phase.
  • Low porosity articles can also be obtained from different particle size distribution combinations, by adjusting sintering times and temperatures.
  • Table 5 An additional example showing a reasonable mechanical and physical chemical performance is summarized in, Table 5 and the properties of this material can be found in Table 6.
  • the mold is filled up with frits of a particle size distribution as stated in Table 5 and covered with a layer of colorless frit having particle size distribution (-2+1 mm) . Pieces are treated at 1000°C during 40 minutes.
  • Table 6 lists the mechanical and physical chemical properties of the sintered glass the composition of which is presented in Table 2 above.
  • Pieces of circa 60 x 90 mm and weighting approximately 85 g are manufactured from glass particles having the composition of Table 2, according to particle size distribution conditions and thermal treatments shown from Table 7 to Table 10.
  • T thermal treatment temperature
  • t dwell period in the temperature level
  • T ⁇ cooling rate
  • isc isothermal treatment that is, the sample is placed inside the preheated furnace straight in the thermal treatment temperature.
  • Table 7 lists data for a sample having particle size distribution between 1 and 2 mm, continuous in this interval, obtained by milling in a mortar and separation in laboratory sieves .
  • Table 8 below lists samples of particle size distribution between 2 and 4 mm, continuous in this interval, obtained by milling in a mortar and separation with laboratory sieves .
  • the expression “stretch” means that the surface has turned into a single, smooth and non-segmented film, no longer keeping the features of the first topography of the compact particles, before sintering.
  • Table 9 lists the properties of a sample with a mixture of particle size distributions in the amount of 71 wt % between 2 and 4 mm and 29 wt % smaller than # 100 (that is, smaller than 150 ⁇ m) and continuous in the intervals, obtained by milling in a mortar, separation with the aid of laboratory sieves and further mixture.
  • Table 10 lists samples having a continuous particle size distribution ⁇ 0.85 mm, (that is, below sieve # 20), obtained by milling and industrial separation, 60 minutes treatments at T.
  • Tables 11 and 12 below illustrate the porosity that can be obtained from the materials used in the invention.
  • Table 11 lists frit densities and porosity having particle size distribution between 0.5 and 1 mm, isothermically treated for sintering at 700°C and 750°C at the indicated times.
  • Table 12 lists further examples of sintered frits that reached 100% densification that is approximately zero porosity at the surface, at a depth of the order of the particle size used.
  • Porosity is assessed using Methods ASTM C 373 -88 "Standard Test Method for Water Adsorption, Bulk Density, Apparent Porosity, and Apparent Specific Gravity of Fired Whiteware Products", and ASTM 693-84 , "Standard Test Method for Density of Glass by Buoyancy".
  • the more immediate use of the partially crystallized glasses and glass-ceramics obtained by sintering is in wall tiles.
  • the highly crystallized glass-ceramics which are therefore harder, can also be used as floor tiles, in relatively large blocks, of the order of 1 m 2 , or smaller.
  • Applications in residence and public, commercial and eventually industrial building floors and facades, in laboratories provided with sanitary control, are foreseen.
  • Basins and flat stoppers for kitchens and bathrooms can also be manufactured.
  • the inventive process can also be directed to obtain curved pieces.
  • the materials produced through the inventive process can be adapted to the manufacture of toilets, lavatory basins, kitchen utensils, filters, provided they are combined to suitable parameters of for example binding additives and lubricants, shaping methods, burning with dimensional control, etc.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Geochemistry & Mineralogy (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Glass Compositions (AREA)

Abstract

Cette invention concerne la fabrication d'articles en verre et vitrocéramique selon un procédé reposant sur le système soude-chaux-silice (NCS). Ce procédé consiste : à préparer des frittes par fusion de compositions NCS appropriées entre 1300°C et 1600°C ; à broyer le mélange en particules de taille correcte, inférieure à 15mm ; à tasser et à fritter les particules entre 720°C et 1100°C de manière à favoriser un écoulement visqueux avant l'apparition d'un phénomène limitant de cristallisation de surface et obtenir une densification maximale ou, en variante, à interrompre le processus de frittage pour obtenir des particules poreuses, les paramètres de fabrication étant optimisés à l'aide d'un modèle mathématique et d'un algorithme qui permettent de conférer au produit final la porosité et la cristallinité requise. Sont également décrits les articles en verre et en vitrocéramique ainsi obtenus.
PCT/BR2004/000079 2003-05-26 2004-05-26 Articles en verre et en vitroceramique et procede de fabrication WO2004103921A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BRPI0301484-3 2003-05-26
BRPI0301484A BRPI0301484B1 (pt) 2003-05-26 2003-05-26 processo para obtenção de artigos vítreos e vitrocerâmicos e artigos vítreos e vitrocerâmicos assim obtidos

Publications (1)

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WO2004103921A1 true WO2004103921A1 (fr) 2004-12-02

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110217540A1 (en) * 2010-03-02 2011-09-08 Dow Global Technologies Inc. Substrates containing a polymer layer and methods for making the same
CN103359943A (zh) * 2013-08-05 2013-10-23 广东高微晶科技有限公司 多晶型的微晶玻璃陶瓷复合板及其制备方法
US10710918B1 (en) 2018-02-19 2020-07-14 Owens-Brockway Glass Container Inc. Method of manufacturing a hollow glass article having a container shape
CN112379637A (zh) * 2020-11-04 2021-02-19 华中科技大学 一种插铣加工参数优化方法、系统、设备及介质
CN113227006A (zh) * 2018-12-21 2021-08-06 卢卡·通切利 由基础混合物制造有色玻璃-陶瓷板坯物品的方法、用于制造基础混合物的玻璃料以及如此获得的有色玻璃-陶瓷板坯物品
CN114920442A (zh) * 2022-05-12 2022-08-19 信和光能(安徽)有限公司 一种硅硼玻璃生产工艺
CN116981648A (zh) * 2021-03-12 2023-10-31 株式会社村田制作所 玻璃陶瓷材料、层叠体以及电子部件
CN118145890A (zh) * 2024-03-12 2024-06-07 广东明泰盛陶瓷有限公司 一种微晶化日用陶瓷制品的制备工艺

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US3825468A (en) * 1969-07-25 1974-07-23 Owens Illinois Inc Sintered ceramic
US5061307A (en) * 1990-01-05 1991-10-29 Nippon Electric Glass Co., Ltd. Crystallized glass having natural-marble-like surface patterns and method of producing the same
US5403664A (en) * 1992-05-11 1995-04-04 Nippon Electric Glass Co., Ltd. Marble-like glass ceramic
US5649987A (en) * 1994-05-10 1997-07-22 Schott Glaswerke Process for producing tabular building and decorative materials similar to natural stone
JP2002068763A (ja) * 2000-08-31 2002-03-08 Central Glass Co Ltd 装飾ガラスの製造方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3825468A (en) * 1969-07-25 1974-07-23 Owens Illinois Inc Sintered ceramic
US5061307A (en) * 1990-01-05 1991-10-29 Nippon Electric Glass Co., Ltd. Crystallized glass having natural-marble-like surface patterns and method of producing the same
US5403664A (en) * 1992-05-11 1995-04-04 Nippon Electric Glass Co., Ltd. Marble-like glass ceramic
US5649987A (en) * 1994-05-10 1997-07-22 Schott Glaswerke Process for producing tabular building and decorative materials similar to natural stone
JP2002068763A (ja) * 2000-08-31 2002-03-08 Central Glass Co Ltd 装飾ガラスの製造方法

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110217540A1 (en) * 2010-03-02 2011-09-08 Dow Global Technologies Inc. Substrates containing a polymer layer and methods for making the same
CN103359943A (zh) * 2013-08-05 2013-10-23 广东高微晶科技有限公司 多晶型的微晶玻璃陶瓷复合板及其制备方法
US10710918B1 (en) 2018-02-19 2020-07-14 Owens-Brockway Glass Container Inc. Method of manufacturing a hollow glass article having a container shape
CN113227006A (zh) * 2018-12-21 2021-08-06 卢卡·通切利 由基础混合物制造有色玻璃-陶瓷板坯物品的方法、用于制造基础混合物的玻璃料以及如此获得的有色玻璃-陶瓷板坯物品
CN113227006B (zh) * 2018-12-21 2023-05-12 卢卡·通切利 由基础混合物制造有色玻璃-陶瓷板坯物品的方法、用于制造基础混合物的玻璃料以及如此获得的有色玻璃-陶瓷板坯物品
CN112379637A (zh) * 2020-11-04 2021-02-19 华中科技大学 一种插铣加工参数优化方法、系统、设备及介质
CN116981648A (zh) * 2021-03-12 2023-10-31 株式会社村田制作所 玻璃陶瓷材料、层叠体以及电子部件
CN114920442A (zh) * 2022-05-12 2022-08-19 信和光能(安徽)有限公司 一种硅硼玻璃生产工艺
CN114920442B (zh) * 2022-05-12 2024-05-28 信和光能(安徽)有限公司 一种硅硼玻璃生产工艺
CN118145890A (zh) * 2024-03-12 2024-06-07 广东明泰盛陶瓷有限公司 一种微晶化日用陶瓷制品的制备工艺

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